Percussion type photoflash lamp

ABSTRACT

To hold a counter anvil in place in the percussion tube of the lamp, a headed pin forming the anvil is supported in the capshaped closed end of the tube. The anvil abuts the tube end with its head. The head length is about twice its diameter so that the contact surface is sufficiently large for centering of the anvil inside the tube. The anvil portion of the pin extends in the percussion zone and carries an ignition material. The diameter of the anvil portion is selected such that there remains a sufficiently large gap between anvil and tube.

[Him 1 [1 1 [111 3,836,317 llsultas Sept, 17, 1974 [54] PIECUSSION TYPEPHOTOFLASH LAMP 3,776,685 12/1973 Senft et al 431 93 [75] Inventor:Josef Lukas, Augsburg, Germany [73] Assignee'Patent-Treuhand-Gesellschaft fur Primary Examinercarro" Domy elemrischeGluhlampen mbH Attorney, Agent, or Firm-Flynn & Frishauf 9 Munchen,Germany [22] Filed: June 15, 11973 [57] ABSTRACT PP 370,329 To hold acounter anvil in place in the percussion tube of the lamp, a headed pinforming the anvil is sup [30] Foreign Applicatiun Priority Dam ported inthe cap-shaped closed end of the tube. The J 20 1972 G 2230005 anvilabuts the tube end with its head. The head length emmy is about twiceits diameter so that the contact surface is sufficiently large forcentering of the anvil inside the gill. tube The anvil portion of thepin extends in the cussion Zone and carries an ignition material. The di[58] Field of Search 431/92, 93, 94 ameter of the anvil portion isSelected Such that there [56] IR eferences Cited remains a sufficientlylarge gap between anvil and tube. UNITED STATES PATENTS 3,567,351 3/1972Harvey .I 431/93 5 Claims, 2 Drawing Figures PATENTED SEP 1 7 I974 FIG.2

FIG. I

PERCUSSION TYPE Pll-IIOTOFLASIHI LAMP The present invention relates tophotoflash lamps which comprise a light-transmissive envelope containingcombustible material and a combustion-sustaining substance, and on whicha mechanically releasable ignition or primer is provided, comprising asmall metal tube sealed into the envelope. The tube is in communicationwith the interior of the envelope; the end thereof which projectsexternally of the envelope is closed and contains a percussive ignitingmaterial.

It has been proposed to apply the igniting material to a wire which issecured inside the tube and functions simultaneously as a carrier forthe substance and as an anvil. The wire end is thickened to form a headwhich is used for preliminary centering when inserting it in the tubeand for securing it therein. At about half its length, the wire isprovided with three or four lugs which may be formed, for instance, bybeads and which are used to center the wire in the tube. The length ofwire extending between head and lug is coated with igniting material.

The wire is usually coated by immersing it in ignition paste. Theresulting coating on the wire head is undesirable and, consequently, isremoved by wiping it off in an additional working step. Due to therequired lugs and the coating procedure with subsequent wiping off,manufacture of the anvil becomes very complex; it is therefore importantfor simplification of the manufacturing process and price reduction, todevelop a more simple anvil design.

SUBJECT MATTER OF THE INVENTION Inside the metal tube in the regionprojecting externally of the lamp envelope, a headed metal pin isdisposed to function as an anvil; its head is supported and centeredinside the tube. The pin section extending in the percussion zone is ofsmaller diameter than the head, and is coated with an ignition pastee.g., applied by dipping, while holding the pin on the head.

The head of the anvil has a length of up to about two times its diameterto insure satisfactory centering of the metal pin in the tube evenwithout the provision of additional lugs at half its length. Since thatportion of the anvil previously provided with lugs may now be omitted,the length of the anvil is reduced. This permits not only a reduction inlength of the photoflash lamp but also of a possible fixture such as,for example, a flashcube. The headed pin anvil permits coating withigniting material by immersion dippingwhile, the head is supported andthus kept free of coating. It will therefore remain free of coatingmaterial and not even have a thin film, or residues, or traces thereon.

The invention will be described by way of example with reference to theaccompanying drawings, wherein:

FIG. 1 is a part and vertical section of the ignition device;

FIG. 2 is another embodiment of the ignition device, partly in section.

The ignition device illustrated in FIG. I for mechanically ignitablephotoflash lamps comprises a tube 1 which is deep-drawn from coppersheet and, is capped off at its closed end 2. The open end 3 of tube 1is slightly conically expanded which considerably improves sealing intothe glass envelope 4 shown in fragmentary form only. An anvil 5, in formof a headed pin is introduced in the tube e.g. by dropping it in. Head 6of anvil 5 is locked inside the cap-shaped end 2. The head length isabout twice its diameter; thus the contact surface between anvil 5 andtube 1 is relatively large to ensure centering of the anvil within thetube.

Starting from head 6, the anvil 5 tapers towards section 7 extendingacross the percussion zone to a diameter which is slightly smaller thanthat of head 6. Section 7 extending across the percussion; zone iscoated, for instance, by immersion with the percussive igniting material8. The difference in diameter between head 6 and section 7 extendingacross the percussion zone is selected such that there remains a gap ofat least 50 u between coated anvil and tube 1 even when the thickness ofcoating of the igniting material is t. When immersing anvil 5, the head6 remains uncoated because the anvil can be supported at its headportion.

After insertion by dropping the coated anvil 5 head first, into thetube, it is locked in tube 1 by indenting the tube, e.g., forming aring-shaped groove 9 adjacent head 6 where the latter merges withsection 7 extending across the percussion zone.

As is to be seen from FIG. 2, section 10 of the anvil extending acrossthe percussion zone may be of slightly conical design whereby the flamegenerated upon percussive ignition viz. the hot particles ejected fromthe tube are directed more precisely at zirconium shreds (not shown)contained in glass envelope 4.

I claim:

ll. In a photoflash lamp a light-transmissive envelope (6) whichcontains combustible material and a combustion-sustaining substance,

a metal tube (1) sealed in the envelope (4), the tube being incommunication with the interior of the envelope and having a percussionzone intermediate its length, the end (2) of the tube projectingexternally of the envelope being closed;

and anvil means (5) carrying per-cussive igniting material in the tube,

the improvement wherein the anvil means comprises a pin (5, 6, 7)disposed in the tube, the pin having a head (6) and an anvil section(7), the head being supported at the closed end (2) of the tube (l) andbeing in centering engagement inside the tube solely by engagement ofthe head (6) and the closed end. (2) of the tube (1), said tube beingindented (9) imediately above the head of the anvil, and locking thehead in position therein by the indentation (9) of the tube (1), thehead having a length of approximately two times its diameter, its outersurface being in engagement with the end (2) of the tube throughout itslength;

and the anvil section (7) of the pin being of smaller diameter than thehead (6), and tapering from the head to the upper end of the anvil meanswhich lies within the tube and being coated with an ignition paste, saidtube and anvil section being face of any protrusions between theindented portion of the tube and the upper end of said anvil means.

2. A photoflash lamp as claimed in claim 11, wherein the anvil sectionextending across the percussion zone is of cone shape (Ill).

3.. A photoflash lamp as claimed in claim 1, wherein the inner end (3)of the tube l) at its seal to the glass envelope (4) is flared.

4. A photoflash lamp as claimed in claim 1, wherein the head (6) iscompletely free of coating material and the tube is formed with a ringgroove to form the indenforms a holder for immersion in percussionmaterial of tation thereof. the anvil portion only to only coat theanvil portion.

5. A photoflash lamp as claimed in claim 1, wherein UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent No. 3,836,317 Dated September17, 1974 Inventorfls) Josef LUKAS It is certified that error appears inthe above-identified. patent and that said Letters Patent are herebycorrected as shown below:

The priority data should read correctly:

- Germany/ 20 June 1972, number 2230,052

Signed and sealed this 4th day of February 1975.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents

1. In a photoflash lamp a light-transmissive envelope (4) which containscombustible material and a combustion-sustaining substance, a metal tube(1) sealed in the envelope (4), the tube being in communication with theinterior of the envelope and having a percussion zone intermediate itslength, the end (2) of the tube projecting externally of the envelopebeing closed; and anvil means (5) carrying percussive igniting materialin the tube, the improvement wherein the anvil means comprises a pin (5,6, 7) disposed in the tube, the pin having a head (6) and an anvilsection (7), the head being supported at the closed end (2) of the tube(1) and being in centering engagement inside the tube solely byengagement of the head (6) and the closed end (2) of the tube (1), saidtube being indented (9) imediately above the head of the anvil, andlocking the head in position therein by the indentation (9) of the tube(1), the head having a length of approximately two times its diameter,its outer surface being in engagement with the end (2) of the tubethroughout its length; and the anvil section (7) of the pin being ofsmaller diameter than the head (6), and tapering from the head to theupper end of the anvil means which lies within the tube and being coatedwith an ignition paste, said tube and anvil section being face of anyprotrusions between the indented portion of the tube and the upper endof said anvil means.
 2. A photoflash lamp as claimed in claim 1, whereinthe anvil section extending across the percussion zone is of cone shape(10).
 3. A photoflash lamp as claimed in claim 1, wherein the inner end(3) of the tube (1) at its seal to the glass envelope (4) is flared. 4.A photoflash lamp as claimed in claim 1, wherein the tube is formed witha ring groove to form the indentation thereof.
 5. A photoflash lamp asclaimed in claim 1, wherein the head (6) is completely free of coatingmaterial and forms a holder for immersion in percussion material of theanvil portion only to only coat the anvil portion.